Presently there are drain covers for use on driveways, patios, walk-out basement doors below grade, interior spaces, window wells and other dry land flat surfaces that are subject to flooding. Most such drain covers have a generally circular planar shape with either holes or slots therein to permit water to drain there through while preventing debris from entering the drainage pipe and water removal systems. Such drains are typically connected, via pipes, to storm sewer or other water removal systems. While it is desirable to remove water alone from such surfaces, often times the surfaces will have leaves, grass, soil and other debris thereon. Municipalities typically are desirous that only water be permitted through to storm sewer systems; in order to accomplish this, the drain covers are typically generally solid with small perforations thereon to allow water, and only tiny particles of debris, to enter and proceed to the storm sewer.
In certain situations, municipalities must make some allowance for the entry of debris into water removal systems, or risk dangerous flooding. For example, on road surfaces, the presence of water can result in dangerous hydroplaning and other flooding conditions causing safety hazards. For those situations culvert drainage systems have been developed wherein a drain is placed against an elevated curb, with a partially open top surface and a depending perforated skirt. However, these types of drains are only possible against curbs as the skirt portion is typically quite elevated (so as to be effective only during periods of high water) and would prove a high obstacle on a flat surface. Patents covering these types of culvert systems and systems for treating water runoff from such, include U.S. Pat. Nos. 7,534,355, Lockeiman et al. Storm Drain Filter With Variable Flow Capacity; and 8,017,004, Crumpler, Storm Drain and Filter System; and 7,332,091, Peters, Jr. et al., Process for Treating Storm Water. Each of these shows variable sized openings but are of a type that can only be used in the side of the curb on a roadway, due to their large size and shape and which could not be adopted for flat surface use.
However, in areas of generally open flat areas, such as patios and driveways that are in proximity to a house or other structure, the use of drains that have small holes or slots so as to permit drainage of water alone, often cause flooding situations when the small holes or slots become blocked by debris. This flooding has deleterious effects on the nearby house or structure and/or other property, causing damages that are often measured in the thousands of dollars. The allowance of leaves or other debris into storm sewers or other drainage systems can be otherwise managed and would cause less damage than that otherwise suffered. For example, U.S. Patent Application Publication No. 2005/0247612, Glassheim, Silt and Debris Filtering System for Storm Drains, tries to solve the problem by capturing the large debris within a drain, but there is a requirement for the user to occasionally come and clear out the debris trap, and in the interim flooding can occur. Further, the device shown is more appropriate for use at curbside or within a storm sewer system, as the device is placed at the opening of the drain within the storm sewer and likely would not fit within a smaller drain used on a flat surface. U.S. Pat. No. 6,793,811, Fleischmann, Runoff Drain Filter with Separately Removable Cartridges, shows a more modern approach to run off filters, but suffers the same issues and is also not appropriate to flat surface drainage. Further, the height of drains used on flat surfaces, particularly those where automobile or pedestrian traffic is common, must be low profile so that the drain covers do not prove an impediment or hazard to automobiles or pedestrians traversing the flat surface.
It would be desirable to have a drain cover that would block debris from entering a storm sewer system until the threat of flooding occurs and thereafter concomitantly permit drainage of large debris until the threat is alleviated.
In the past, some surface drains have been made of a type having small openings to permit water and small debris to enter and which are typically mounted such that the top surface of the drain cover is flush with the surface to be drained. For example, U.S. Pat. No. 4,655,913, Boersma, Adjustable Drain Cove and Design patent No. 256,948, Boersman, Drain Cover, presents drains wherein small holes are provided for drainage, the device including means to adjust the fit of the cover within the pipe from outside of the cover. However, the '913 and '948 patents suffer the problem that when debris is brought towards the drain, with the natural flow of water, these drains will likely be clogged allowing the surface to flood. In U.S. Pat. Nos. 134,978, Clapp, Gratings for Sewer Inlet; 5,724,684, Paar, Raised Strainer; 7,300,573, Trangsrud, Catch Basin Filter; D606,174, Martin, Debris Cage; and Des. 388,725, Trampush, Strainer for Downspouts, various types of surface strainers are provided each having either an elevated portion very high above the surface, or offering only minimal allowance for the removal of large debris. The height of the devices claimed and shown in these patents makes them unsuitable for flat surfaces where pedestrians will walk or vehicles will traverse, as the devices will prove an impediment to safe travel.
In addition there are some drains made for the bottoms of pools that are also of a type having an elevation from a flat surface, such as that shown in U.S. Pat. No. 6,588,029, Mullings, Safety Drain Guard for Swimming Pools and Spas and 6,393,631, Schroader, Drain Safety Cover System and Method, and while larger openings are shown in combination with smaller openings, these drains are designed to clean the pool and not to drain a flat surface that is suppose to remain dry. Such systems are further designed to prevent persons from being trapped by suction on a pool drain and thus provide different levels of water intake so that vacuum created by suction can be broken more easily. Further, the designs have a similar flaw in that they are raised above the surface such that the use of such drains on flat dry surfaces would prove a hazard to travel; their placement in a swimming pool, particularly in the deep end, causes no such hazard.
Objects and advantages of the present invention will become apparent as the description proceeds.